1. Field of the Invention
The present invention relates to two embodiments of an ice auger cutting head characterized by flat sharp serrated replaceable cutting blades disposed at the lower end of an upright drive shank which has a spiral flighting or helical auger blade along a substantial portion of its length. The drive shank is rotated to cut down through a body of ice against which the cutting head is advanced for drilling holes through the ice for ice fishing.
2. Prior Art
Fabiano U.S. Pat. No. 5,302,059 shows a drill bit having three (or more) flat replaceable cutting edges equally spaced around the longitudinal axis at the end of the bit. The purpose is said to be to cut smaller chips which are easier to remove, enhancing the cooling of the drill and workpiece. However, the drill is for accurately cutting holes in metal. The radial displacement of each cutting edge from the axis is different.
Kortschage U.S. Pat. No. 3,602,321 is directed to an ice auger intended to be driven from a power take-off of a snowmobile. The cutting edges appear to be the edges of scoop-like elements at the end of a single flight auger.
Taylor U.S. Pat. No. 4,046,207 is directed to an earth auger and discloses the concept of a small diameter pilot hole followed by a series of stepped holes of increasing diameter.
Hein U.S. Pat. No. 3,175,630 is directed to a two-bladed double-flight earth auger and discloses the concept of the cutting edges being slightly beyond the edges of the auger flights to prevent binding of the auger as the hole deepens. This auger also has a lead screw which would make an initial small diameter hole.
Gilbert U.S. Pat. No. 4,074,780 is also directed to an earth auger. It is a single flight auger having a single curved edge blade and a pilot element for making a small diameter pilot hole.
Altonen U.S. Pat. No. 3,786,876 is directed to a single flight ice auger having two replaceable curved blades for cutting a hole slightly larger than the diameter of the auger. Both blades are supported on a single xe2x80x9cattachment piecexe2x80x9d at the end of the auger helix and shank.
Grahl U.S. Pat. No. 5,251,707 is directed to a one-piece propellor-like cutting head having opposed pairs of inner and outer blade edges. The inner blades would cut a pilot hole to be enlarged by the outer blades.
Caswell U.S. Pat. No. 5,950,738 is directed to a single flight ice auger having either one or two replaceable cutting blades. The patent is primarily concerned with means for flaring the bottom end of the hole cut through the ice.
The first two stage embodiment of the ice auger cutting head has two diametrically opposed sharp flat serrated replaceable cutting blades tilted slightly upwardly and having a radius slightly greater than that of the helical auger. Each cutting blade is supported at the leading edge of a partial helical dished concave scoop-like member secured to the shank of the auger and communicating with the helical channel of the auger. The trailing edge of one of these scoops is contiguous with the bottommost edge of the auger blade. A second pair of upwardly tilted smaller cutting blades is positioned below the first pair of blades along a transverse axis which is perpendicular to the transverse axis of the first pair of blades. Each of the smaller blades has an arcuate outer edge with a radius substantially less than that of the other blades and the auger. Each of the small blades is supported at the leading edge of a partial helical dished concave scoop each having a trailing edge connected to the leading edge of one of the first scoops spaced inwardly from the cutting edge of the larger blade. The smaller blades serve to cut a pilot hole of lesser diameter in the ice and the ice chips are carried to the larger scoops. The smaller hole is then enlarged by the larger blades and the ice chips are carried to the surface of the frozen lake or river being fished.
The second single stage embodiment of the ice auger cutting head has three sharp flat serrated replaceable cutting blades equally spaced about the vertical axis of the auger. Each blade tilts upwardly at a slight angle to its outer arcuate edge which has a radius just slightly greater than the radius of the helical auger blade. Each cutting blade is supported at the leading edge of a partial helical dished concave scoop-like member secured to the shank of the auger in a 3-leaf clover arrangement. The pitch of the partial helical scoop is substantially less than that of the helical auger blade. The trailing edge of the scoop opposite from the cutting blade communicates directly with the helical channel of the auger for elevating ice chips to the surface. The trailing edge of one of the scoops is contiguous with the bottommost edge of the helical auger blade.